Infants and other incontinent individuals wear absorbent articles such as diapers to absorb and contain urine and other body exudates. Absorbent articles function both to contain the discharged materials and to isolate these materials from the body of the wearer and from the wearer's garments and bed clothing. Disposable absorbent articles having many different basic designs are known in the art. For example, U.S. Patent Re. 26,152, entitled "Disposable Diaper" issued to Duncan et al., on Jan. 31, 1967, describes a disposable diaper which has achieved wide acceptance and commercial success, and U.S. Pat. No. 3,860,003, entitled "Contractable Side Portions for Disposable Diaper," issued to Buell on Jan. 14, 1975, describes an elastic leg cuff disposable diaper which has achieved wide acceptance and commercial success, both patents being hereby incorporated by reference.
Many of the known absorbent articles, however, have a tendency to sag or gap away from and to slide/slip down on the body of the wearer during use. This sagging/gapping and sliding/slipping is caused by the relative motions of the wearer as the wearer breathes, moves and changes position, by the downward forces generated when the absorbent article is loaded with body exudates, and by the deformation of the materials of the absorbent article itself when subjected to such wearer's motions. This sagging/gapping and sliding/slipping of the absorbent article can lead to premature leakage and poor fit of the absorbent article about the wearer.
Conventional disposable diapers are typically designed to fit high on the abdomen of the wearer and down on the thighs such that the diaper fits in the zones of the wearer that are subject to dynamic motion (and thus dynamic forces) during use. These dynamic motions and forces, especially by the abdomen bulging and contracting, tend to deform the materials making up the diaper and tend to push the diaper away from the body. Thus, the diaper tends to sag/gap away from the body. The closure system of the diaper is also typically designed to form a defined dimension of the waist and leg openings and a line of tension (imparts a tensile force along a line) about the wearer to secure the diaper of the wearer. However, this defined waist dimension created by the closure system cannot accommodate the changes in body dimension caused by wearer movement such that the diaper tends to slide/slip down on the wearer when the dimension of the abdomen of the wearer becomes smaller than the defined dimension formed by the closure. Further, when the abdominal dimension becomes larger than the defined dimension formed by the closure system, the diaper tends to move to a different position on the wearer (i.e. to the area of minimum circumference) or the diaper tends to be so tight on the abdomen that the diaper can mark the skin or be uncomfortable to wear. The absorbent core and other stiff nonelastic members of the diaper typically fit in the zones of the abdomen or legs that undergo such dynamic forces that the absorbent core bunches and is pushed downward or inward by the dynamic forces resulting in further gapping/sliding of the product on the wearer.
In order to more snugly fit absorbent articles about the wearer, certain commercially available absorbent articles have been provided with elastic features about the waist, hips, or legs. An example of a disposable diaper with an elastic waist feature which has achieved wide acceptance and commercial success is disclosed in U.S. Pat. No. 4,515,595 which issued to Kievit et al., on May 7, 1985, and is incorporated by reference. An example of a disposable diaper with an elastic leg cuff is disclosed in the previously mentioned U.S. Pat. No. 3,860,003. A further example of a disposable diaper with elastic side panels that fit over the hips of the wearer is disclosed in U.S. Pat. No. 4,857,067 which issued to Wood et al., on Aug. 15, 1989, which is also incorporated by reference. The elastic features are designed to expand and contract with the wearer's motions and to maintain the fit of the absorbent article about the wearer during use (i.e., provide sustained dynamic fit). However, it has been found that absorbent articles having elastic features also have a tendency to sag/gap and slide/slip during use.
In addition to addressing problems with the fit and sustained fit of absorbent articles, much attention has been focused on improving the absorbent core structures that function to absorb exudates discharged from the body of the wearer. Commonly, these cores include a conventional absorbent gelling material (referred to herein as an "AGM" material) or a conventional superabsorbent material dispersed in a batt of cellulose fibers. While such core structures typically exhibit good absorbency characteristics, they tend to be limited in their ability to return substantially to their original configuration after being deformed under normal wear situations.
Recent developments in the absorbent article industry have included improved stretchable articles. However, the ability to fully utilize suitable articles is often limited by the lack of integrity and shape retention offered by existing core elements. Thus to improve the overall usefulness of these absorbent articles made with the improved stretchable features, there has arisen a need for core elements which are not greatly limited by a failure to allow for movement of the wearer.
A stretchable absorbent article, namely a sanitary napkin, is disclosed in co-pending commonly assigned PCT application No. W 93/01785, entitled "Stretchable Absorbent Articles." An absorbent elastomeric wound dressing is disclosed in U.S. Pat. No. 4,957,795 (Riedel).
Additional background literature that may be of interest include U.S. Pat. Nos. 3,856,013 (Dulle); 4,229,548 (Sattlegger et al.); 4,341,214 (Fries et al.); 4,554,297 (Dabi); 4,584,324 (Bauman et al.); 3,916,900 (Breyer et al.); 4,394,930 (Korpman); 4,664,662 (Webster); 5,149,720 (DesMarais et al); 4,834,735 (Alemany); 4,610,678 (Weisman et al); 4,673,402 (Weisman et al.); U.S. patent application Ser. No. 08/085,537; entitled "Elastomeric Adhesive Foam;" filed Jun. 30, 1993 in the names of Litchholt and Lodge; and U.S. patent application Ser. No. 08/085,237; entitled "Method of Making an Elastomeric Adhesive Foam and of Elasticizing Garments;" filed Jun. 30, 1993 in the names of Litchholt and Lodge, all of which are incorporated herein by reference.
Attention has thus continued to be focused on developing flexible highly absorbent cores which are useful in association with stretchable articles. For example, U.S. Pat. No. 5,268,224, which issued Dec. 7, 1993, to DesMarais, et al., entitled "Absorbent Foam Materials for Aqueous Body Fluids and Absorbent Articles Containing Such Materials" which is incorporated by reference herein, relates to absorbent foam materials suitable for use as or in the absorbent cores of absorbent articles. Such foamed materials typically comprise hydrophilic, flexible open-celled structures which are preferably prepared by polymerizing high internal phase water-in-oil emulsions having pore volumes of from about 12 to 100 ml/g, and a capillary action specific surface area of from about 0.5 to 5.0 m.sup.2 /g.
With the advent of more flexible, highly absorbent cores and core materials, attention has turned to utilizing such materials in the most efficient and effective manner possible. Thus, it would be advantageous to provide an absorbent article that provides better fit, reduced leakage, and wearer comfort. It would further be advantageous to provide an absorbent article which has reduced sagging and gapping as well as reduced overall sliding/slipping of the absorbent article and/or the absorbent core on the wearer during use.
It is therefore a primary object of the present invention to provide absorbent articles having improved dynamic fit and sustained fit by utilizing uniquely shaped absorbent cores made from a resilient absorbent material in association with a uniquely designed chassis.
It is a further object of the present invention to provide an absorbent article providing increased comfort for the wearer by providing freedom of motion for the wearer and minimizing the effects of forces caused by wearer's movements on the product's stability.
It is also an object of the present invention to provide an absorbent article including a specifically shaped absorbent core designed to fit within the low motion zone of the wearer, therefore, minimizing the effects of wearer movement on the overall fit of the article.
It is a further object of the present invention to anchor the absorbent article about the perimeter of the low motion zone (otherwise referred to herein as the area of minimum circumference) to achieve sustained dynamic fit.
It is also an object of the present invention to provide a closure system and containment assembly (chassis) design that anchors the absorbent core in the low motion zone of the wearer to enhance the sustained dynamic fit.
It is a further object of the present invention to provide a containment assembly (chassis) design, closure system and an absorbent core shape cooperating to reduce sagging and gapping as well as overall sliding/slipping of the absorbent article during use.
Yet, another object of the present invention is to improve the geometric location of the fastening tabs and the diaper fastening system to enhance the sustained fit of the absorbent article.
Still another object of the present invention is to provide a containment assembly (chassis) design which results in the absorbent article having improved aesthetic characteristics.
These and other advantages of the present invention will be more readily apparent when considered in reference to the following description and when taken in conjunction with the accompanying drawings.